Light-sensitive cell



Jan. 9, 1934. A. w. CARPENTER 1,942,958

LIGHT SENSITIVE CELL Filed Sept. 10, 1930 (0A T/Nc; 61/45 INVENTOR Apr/7 w? w 64 RPENT'ER Ah'ORNEY Patented Jan. 9, 1934 UNITED STATES PATENT OFFICE to United Research Corporation, New York,

N. Y., a corporation of Delaware Application September 10, 1930 Serial No. 480,961

4 Claims.

This invention relates to light-sensitive cells, and particularly to the conductive electrodes thereof.

When light-sensitive cells are made with a 5 tenuous metal layer as an electrode on an insulating support it is desirable that the metal be sufllciently adherent to the support to retain its form and position, be easy to produce, and be of such form and character as to favor the operation of the cell.

An object of this invention is to produce a lightsensitive cell in which the electrode material is more firmly adherent to the base than in prior cells.

Another object is to avoid angles in the outlines of the interdigitated electrodes.

Still another object is to produce, in a lightsensitive cell, a sinuous or arcuate trace, dividing a conductive layer into electrodes without producing angular corners therein.

A further object is to produce a light-sensitive cell electrode which is adapted to rapid and easy manufacure.

A still further object is to produce an electrode construction in which strains tending to loosen the electrode metal from the base are reduced.

In the prior art of the construction of lightsensitive cells it has been common to use a pair of interdigitated electrodes, carried upon an insulating support, with the.light-sensitive material bridging the open trace between the interdigitated portion of the electrodes. The previous electrodes have, however, been made in a rec tangular form with square corners and sharp angles at the respective ends of the digital members.

It is found, however, that the corners and angles are sources of weakness in the construction, because of the fact that the corners are poorly supported against shrinkage strains and tend to peel off, and the angles are places of weakness at which cracks may start. Such cracks and peeled corners tend to cause separation of the conductive electrode from the supporting material, and also exert an eifect upon the light-sensitive material.

It is also found that the square corners appear to have an effect upon the crystal structure of the light-sensitive material which injures the sensitivity and performance of the cell. It is further found that when the electrodes are produced by means of a trace drawn through the metal film, the drawing of a trace with square corners is a laborious and time consuming operation.

This invention provides a simple, useful and improved electrode arrangement for a lightsensitive cell, in which the interdigitated portions are formed by a sinuous trace in a metal film, the trace being produced without sharp corners, and with arcuate portions at the ends of the tangent parts of the trace, which form the interdigitated portions.

By this simplification of construction, it becomes possible to prepare the electrodes with much less labor and in much less time, the resulting electrodes are much stronger, and much more firmly adherent to the base material, and the deposit of sensitive material applied thereon shows a substantially increased sensitivity and response, and a reduction in ground noise.

These objects are thus obtained by the use of a trace in a metal coating having substantially parallel tangent portions and arcuate connecting portions.

Other objects and structural details of the invention will be apparent from the following description when read in connection with the accompanying drawing wherein:

Fig. 1 is an enlarged view of the sensitive portion of a light-sensitive cell, showing a glass support member and the interdigitated portions of the electrodes, and

Fig. 2 is a similar view of the base, electrodes, and sensitive material, of a light-sensitive cell, showing the electrodes, the sinuous trace, and the applied light-sensitive material.

Referring to the figures, a foundation member 1 is provided, which may desirably be a glass plate, upon whichis applied a layer of conductive metal2 such as platinum. In the metal layer 2 is formed a sinuous trace 3 comprising a plurality of substantially parallel portions 4joined by arcuate portions 5. The trace may be continued in the form of end portions 6 which complete the separation of the respective halves of the metal coating 2 into electrically isolated electrodes. The light-sensitive material 7, which may be selenium or other suitable substance, may then be applied by any appropriate means such as subliming or by application in a plastic state over the interdigitated portion of the electrodes 2.

This electrode construction is peculiarly well adapted to production by a tracing operation, using a pantograph device, in which a guide point following a sinuous trace in a master plate, and directs a cutting point moving at a reduced ratio, to produce the trace in the metalized layer on the glass support as will be understood.

Such apantograph system drawing a plurality of straight line portions with arcuate connecting portions can be operated at a comparatively high rate of speed, for the production of the desired electrodes with ease and rapidity, as contrasted to any other hand or mechanical methods for producing the electrodes.

Furthermore, the absence of corners and angles avoids the points of weakness which are found to exist in a square cornered electrode structure.

In addition, the absence of the corners and angles favors the character of the applied lightsensitive material. The exact phenomenon which occurs is not yet known but it is thought that it is due to a crystal formation around the arcuate portions which is as sensitive and responsive as the crystal structure bridging the tangent portions; as contrasted with the crystal structure at sharp corners which is thought to be in a less sensitive condition than the crystals bridging the tangent portions.

By this construction I have thus produced a light-sensitive cell member which is particularly well adapted to rapid and easy manufacture, which shows substantially greater strength, and a substantially improved performance including improved sensitivity and other features over prior cells.

While only a single embodiment of the invention is disclosed in the above description, it is possible to produce still other embodiments thereof without departure from the inventive concept therein, and it is therefore desired that only such limitations be imposed upon the appended claims as are stated therein, or required by the prior art.

The invention claimed is:

'1. In a light-sensitive cell a plurality of interdigitated electrodes having a separating trace therebetween comprising substantially parallel straight portions and arcuate connecting portions.

2. A light-sensitive cell comprising an insulating support, and a pair of interdigitated electrodes, the edges of the interdigitated portions comprising only curves and tangent lines.

3. A light-sensitive cell comprising an insulating foundation member, and a plurality of adherent interdigitated electrodes thereon, the interdigitated portions being free from sharp corners.

4. In a light-sensitive cell, a pair of electrodes separated by a sinuous trace having only tangent and arcuate portions, and a layer or crystallized light-sensitive material bridging said trace.

ARTHUR W. CARPENTER. 

